(1) Field of the Invention
The present invention relates to an inspection method of an electric part such as a fuse and terminal fittings, to an inspection apparatus of an electric junction box for inspecting whether or not an electric part such as a fuse having an item symbol, which should be mounted on a mount, is mounted, and to an inspection apparatus of a terminal fittings for inspecting the quality of the terminal fittings mounted on an insulator.
(2) Description of the Related Art
Generally, on a motor vehicle as a mobile unit, there are mounted various electronic equipment, for example, lamps such as headlamps and tail lamps, and motors such as a starter motor and a motor for an air-conditioner.
In order to supply the electric power to the various electronic equipment, there are disposed junction blocks at suitable positions in the motor vehicle. In the junction block, wiring boards having printed-wiring boards and bus bars are laminated, into which various electric circuit units are integrated, thereby the junction block is constituted.
Since the junction block may have fuses, relays and bus bars, the junction block may be called as a fuse block, relay box, or an electric junction box as the general term. In this specification, the aforementioned fuse block, relay box and junction block are hereinafter called an electric junction box.
In such a junction box, various electric parts such as fuses, relays, diodes and fusible links are mounted. Each terminal of these electric parts is connected to the wiring board. The junction box electrically connects wires, which are connected to the power sources or loads, to the various electric parts in accordance with a predetermined pattern.
For example, a fuse, which is one of the aforementioned electric parts, has a plurality of item symbols having different capacity. On the outer surface of the fuse, there is shown a mark (for example, 10A and 20A) according to the permissible current. Generally, in the electric junction box, there are mounted fuses having a plurality of item symbols.
When the electric junction box, in which fuses having a plurality of item symbols are mounted, is assembled, a worker mounts each fuse having a required permissible current on a corresponding predetermined position in the electric junction box. Thereafter, whether or not each fuse is properly mounted on the corresponding position is judged by carrying out a continuity test for the electric junction box together with the visual inspection thereof.
In addition, the motor vehicle has a wiring harness for supplying the electric power and control signals to the various electronic equipment mentioned above. The wiring harness comprises a plurality of electric wires and connectors, which are connected to ends of the wires. The wire is so-called a coated wire having an electrically conductive core and an electrically insulating coating portion, which coats the core. The connector has a terminal fittings as an electric part and an insulating connector housing.
The terminal fittings is made by bending an electrically conductive sheet metal and has a pressure-welding part to be pressure-welded to the wire and a caulking piece for caulking the wire. The pressure-welding part has a pair of blades for pressure welding. A pair of the blades cut the coating portion of the wire so as to come in contact with the core when the wire is press-fit between a pair of the blades, thus the pressure-welding part is pressure-welded to the wire. The caulking piece caulks the wire by being bent. The connector housing has a plurality of mounts on which the terminal fittings are mounted. The connector housing mounts the terminal fittings thereon by mounting the terminal fittings on the mounts thereof.
After the terminal fittings are mounted on the mounts of the connector housing, the wire is pressure-welded to the pressure-welding part of the terminal fittings and the caulking piece is bent, thus the terminal fittings is fixed to the wire. In this way, the wiring harness is assembled. When the wiring harness is assembled, the quality of the pressure-welding part and the caulking piece of the terminal fittings, which is mounted on the connector housing, have so far been inspected by a known appearance inspection apparatus. Also, the quality of the pressure-welding part and the caulking piece of the terminal fittings, to which the wire is pressure-welded, have so far been inspected by a known appearance inspection apparatus.
The appearance inspection apparatus mentioned above stores one image of a non-defective terminal fittings in advance and another image of a non-defective terminal fittings to which a wire is pressure-welded in advance. Then, after obtaining an image of the terminal fittings mounted on the connector housing to be inspected and an image of the terminal fittings to which the wire is pressure-welded, the quality of the terminal fittings and that of the pressure-welding state of the wire have so far been judged by comparing these images with the images of the non-defective.
In the aforementioned conventional assembling method of the electric junction box, since a worker selects a required fuse and mounts it on a corresponding position of the electric junction box, there is a possibility that a fuse of improper permissible current is mounted on the corresponding position. Furthermore, since a worker confirms the permissible current of the fuse mounted on the position by the visual inspection, there is a possibility that a fuse of improper permissible current is still mounted on the corresponding position.
In addition, since the terminal fittings is made of sheet metal, if the brightness of the lighting or the positional relation between the terminal fittings and the lighting is changed, the image of the terminal fittings mounted on the connector housing changes. Therefore, when the quality of the terminal fittings is judged by using the appearance inspection apparatus mentioned above, mistake in the judgement, such as judging a non-defective terminal fittings to be defective and judging a defective terminal fittings to be non-defective, can often arise. Therefore, so far it has been difficult to securely judge the quality of the terminal fittings.
As described above, it has been difficult to securely judge the quality of a fuse or a terminal fittings with the conventional inspection method.